1. Field of the Invention
The present invention relates to electron microscopic inspection apparatus for semiconductors and, more particularly, to the electron microscopic inspection apparatus for inspecting semiconductor waters.
2. Description of Related Art
In order to enhance the operating speed of semiconductor devices, semiconductor industries have come to adopt less resistive copper wiring instead of aluminum wiring. However, a problem associated with the copper wiring is that, if copper exists in insulations of semiconductors, it diffuses ten times as fast as aluminum and this deteriorates the device performance. Thus, copper as an impurity should be eliminated completely out of semiconductor fabrication processes. Accordingly, some semiconductor fabrication equipment has been developed to be dedicated to semiconductor production including a copper wiring process (Nikkei Microdevices, February 1999). For example, electroplating apparatus has been contrived to protect the underside surface of a wafer from being contaminated with copper (Nikkei Microdevices, November 1999). Such apparatus is dedicated to semiconductor production including a copper wiring process and contrived to prevent copper impurities from being mixed into semiconductor constituent substances, but a single unit of such apparatus is not designed to process wafers on which non-copper wiring was performed as well as wafers on which copper wiring was performed.
Meanwhile, as disclosed in JP-A No. 260776/2000, there has been proposed an idea to prevent copper diffusion on the wafer side not the wafer fabrication equipment side, but a dedicated process must be added to implement this.
For the purpose of inspecting semiconductor wafers, electron microscopic inspection apparatus such as a metrological scanning electron microscope (SEM) or the like is used. At the present, the electron microscopic inspection apparatus for semiconductor wafers is used such that units of such apparatus provided to inspect wafers on which copper wiring was performed are completely distinct from units of such apparatus provided to inspect wafers on which non-copper wiring was performed. Consequently, if both copper wiring and non-copper wiring processes are included in the entire process of fabricating a specific semiconductor device, the number of required units of electron microscopic inspection apparatus increases by a factor of 1.5 on an average as compared with the process only including the conventional aluminum wiring, though the factor varies, depending on the ratio between both wiring processes.